JP2007234956A - Inspection system of semiconductor element, and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer inspection system which prevents an electrostatic breakage of a wafer and can correctly carry out an inspection of electrical characteristic of the wafer when inspecting the wafer with a probe and its inspection method, and to provide an inspection system which can inhibit a breakage of transistor and occurrence of Vt shift due to a charge in electrical measurement and its inspection method. <P>SOLUTION: The inspection method includes a process which carries out an electrical measurement for a first object to be measured by a first voltage, and a process which carries out an electrical measurement for a second object to be measured different from the first object to be measured by a second voltage lower than the first voltage. The electrical measurement for the second object to be measured is carried out just before the electrical measurement for the first object to be measured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor device inspection system and inspection method. In particular, the present invention relates to an inspection system and an inspection method for performing electrical measurement of a semiconductor element formed on a wafer using a prober.

When a semiconductor chip is formed on a wafer, for example, an apparatus called a prober as disclosed in JP-A-8-335614 is used to inspect the electrical characteristics of each semiconductor chip. This prober includes a probe card having a probe needle that contacts an electrode pad on a semiconductor chip formed on a wafer, and inspects the electrical characteristics of the wafer.
JP-A-8-335614

  The prober includes a test head including a probe card electrically connected to the wafer, a stage on which the wafer is mounted, a stage driving mechanism, a circuit board for driving the probe card, and the like.

  The probe card is provided with probe needles on the lower surface side in accordance with the arrangement of the electrode pads of the semiconductor chip on the wafer. This probe needle contacts the electrode pad of each semiconductor chip on the wafer, and sends and receives signals for inspection.

  The stage carries a wafer and moves in a horizontal direction and a vertical direction by a driving mechanism. The test head includes, for example, a hinge mechanism, and is provided so as to be openable and closable with respect to the housing by rotating around one side with respect to the housing. The test head and probe card are connected by a contact ring. The contact ring is provided with electrode pins, and the electrode pins connect the electrodes provided on the upper surface side of the probe card and the electrodes provided on the lower surface side of the test head. In the probe card, since the probe needle contacts the electrode pad of the semiconductor chip on the wafer, the test head and the wafer are electrically connected via the probe card.

  When inspecting a wafer, first, the wafer is set on a stage. Next, the stage is moved by the drive mechanism, and the stage is raised after the first semiconductor chip to be inspected is opposed to the probe needle on the wafer in accordance with a predetermined inspection order, and the semiconductor is placed on the probe needle. The electrode pad of the chip is brought into contact. Thereby, the wafer and the probe card are connected. Then, the electrical characteristics of the semiconductor chip are inspected by an inspection device connected to the test head.

  When the electrical characteristics of a wafer are inspected by a prober, the wafer may be charged with static electricity due to friction when the wafer is placed on the stage, friction due to movement of the stage by a driving mechanism, or the like. In addition, the probe needle may be charged with static electricity when the probe card is replaced.

  If both are connected while the wafer and probe needle are charged, electrostatic discharge will occur and a voltage exceeding the breakdown voltage will flow to the pattern formed on the semiconductor chip, causing electrostatic breakdown. There's a problem. In addition, there is a problem that static electricity accumulated on a wafer or the like hinders accurate inspection of electrical characteristics.

  Further, the next measurement target may be damaged by static electricity generated during the previous measurement, or a problem of charge-up (Vt shift, etc.) may occur.

  The present invention has been made to solve such problems, and can prevent electrostatic breakdown of the wafer and accurately inspect the electrical characteristics of the wafer when inspecting the wafer by a prober. An object is to provide a wafer inspection system and inspection method. In particular, it is an object of the present invention to provide an inspection system and an inspection method capable of suppressing the breakdown of a transistor and the occurrence of a Vt shift due to charging during electrical measurement.

  In order to achieve the above object, in the inspection method according to the present invention, a step of performing an electrical measurement of a first measurement object with a first voltage; and a second voltage lower than the first voltage; Performing electrical measurement of a second measurement object different from the first measurement object. The electrical measurement of the second measurement object is performed immediately before the electrical measurement of the first measurement object.

  On the other hand, an inspection system according to another aspect of the present invention includes a probe card having a probe needle that is brought into contact with a semiconductor element formed on a wafer; a stage on which the wafer can be moved; and the behavior of the stage is controlled. A control unit. In the control unit, electrical measurement of the first measurement object on the wafer is performed using the first voltage; and the first measurement object is measured using the second voltage lower than the first voltage. Performs an electrical measurement of a second measurement object on a different wafer; and controls to perform an electrical measurement of the second measurement object immediately before the electrical measurement of the first measurement object.

  A resistive element can be used as the second measurement object. On the other hand, at least one of a transistor and a capacitor can be adopted as the first measurement object.

  Further, it is effective when the first measurement object and the second measurement object constitute a TEG (Test Element Group) that is measured simultaneously.

  According to the present invention having the above-described configuration, the second measurement object that performs measurement at a low voltage (or current) is inspected before the inspection of the first measurement object to which a relatively high voltage is applied. Thus, it is possible to remove or reduce charged static electricity. Thereby, it is possible to suppress the destruction of a semiconductor element such as a transistor to be measured due to charged static electricity and the occurrence of a threshold voltage shift of the transistor. In addition, measurement errors due to static electricity can be reduced. Furthermore, it is also a great advantage that there is no need to provide a special configuration or perform a special step for removing the charge.

  Hereinafter, the best mode for carrying out the present invention will be described in detail using embodiments. FIG. 1 is an explanatory view showing a wafer inspection system according to this embodiment of the present invention. The wafer inspection system 10 includes a probe card 12 that is electrically connected to the wafer W, a stage 14 that carries the wafer W thereon, a drive unit 22 for the stage 14, a circuit board that drives the probe card 12, and the like. It consists of a test head 18 and the like.

  The probe card 12 is provided with a probe 16 on the lower surface side according to the arrangement of the electrode pads of the semiconductor chip (measurement target) on the wafer W. The probe 16 is in contact with the electrode pad of the semiconductor chip on the wafer W, and exchanges signals for inspection.

  The drive unit 22 includes a horizontal drive mechanism that moves the stage 14 in the horizontal direction and a vertical drive mechanism that moves the stage 14 in the vertical direction. The horizontal drive mechanism moves the stage 14 in the XY direction.

  The test head 18 and the probe card 12 are connected by a contact ring. An electrode pin is provided on the contact ring, and the electrode provided on the upper surface side of the probe card 12 and an electrode provided on the lower surface side of the test head are connected by this electrode pin.

  The inspection system 10 of the present embodiment further includes a control unit 24. The control unit 24 is connected to at least the test head 18 and the drive unit 22. The control operation by the control unit 24 will be described in detail later.

  Next, the wafer inspection method according to this embodiment will be described. FIG. 2 shows an example of a TEG (Test Element Group) layout diagram to be inspected in the present embodiment. In FIG. 2, TEG1 is a transistor measurement group (N type), TEG2 is a transistor measurement group (P type), TEG3 is a resistance measurement group, TEG4 is a capacitor measurement group (N type), and TEG5 is a capacitor measurement group (P type). is there.

  Conventionally, for example, since TEG1 to TEG5 are measured in order regardless of the type of semiconductor element to be measured, a problem has occurred. For example, when measuring the withstand voltage of a capacitor having a large film thickness (Bvg ± about 180 or more) or the high withstand voltage transistor (BVsd ± about 90 V or more), a high voltage (about ± 90 to ± 200 V) is used. Since this is applied, charge (static electricity) is generated between the probe needle 16 and the head 18, and destruction of the element or Vt (threshold) shift occurs when the next element (transistor or the like) is measured.

  Here, “BVsd” represents a withstand voltage voltage between the source and the drain of the transistor, that is, a voltage value when a current or voltage is applied between the source and the drain of the transistor and a current exceeding a determination current flows. “Bvg” indicates a withstand voltage of the capacitor film, that is, a voltage value when a voltage is applied between the gate and the ground of the capacitor film and a current exceeding a determination current flows. “Vt” indicates a voltage at which the transistor is turned on, that is, a threshold voltage.

  In this embodiment, the measurement order is changed depending on the type (measurement voltage or current) of the semiconductor element (TEG) to be measured. In the present embodiment, for example, the inspection is performed in the order of TEG1-TEG3-TEG2-TEG3-TEG4-TEG3-TEG5-TEG3. That is, the resistance measurement group (TEG3) is always inserted before the measurement of the transistor measurement group (TEG1, TEG2) and the capacitor measurement group (TEG4, TEG5). Such control of the measurement order is achieved by controlling the drive unit 22 by the control unit 24. Usually, the resistance is measured by applying a current, but the actual applied voltage is about several V to 50 V at the highest. The actual measurement time for each TEG is about 70 seconds, and the measurement interval between TEGs is about 1 second.

  When inspecting a wafer, first, the wafer W is set on the stage 14. Next, the stage 14 is moved by the drive unit 22, and the stage 14 is raised after the first semiconductor chip (TEG) to be inspected is opposed to the probe 16 on the wafer W in accordance with the inspection order described above. The electrode pad of the semiconductor chip is brought into contact with the probe 16. Thereby, the wafer W and the probe card 12 are electrically connected. A test electric signal (current or voltage) is sent to the semiconductor element on the wafer W by the probe 16. A reply signal from the probe 16 is sent to the control unit 24 via the test head 18. Then, the electrical characteristics are inspected by the control unit 24 or by another inspection device connected to the control unit 24.

  As described above, according to the present embodiment, the inspection of TEG3 that performs measurement at a low voltage (or current) is performed before the inspection of TEG1, TEG2, TEG4, and TEG5 to which a relatively high voltage is applied. Thus, static electricity charged on the probe card 12 or the like can be removed or reduced. Thereby, destruction of semiconductor elements such as transistors and capacitors of TEG1, TEG2, TEG4, and TEG5 and occurrence of threshold voltage shift can be suppressed by the charged static electricity. In addition, measurement errors due to electrostatic charging can be reduced, and measurement accuracy is improved.

The present invention has been described with reference to the embodiments. However, the present invention is not limited to the scope of the embodiments, and the design can be changed as appropriate within the scope of the technical idea described in each claim. Needless to say.

FIG. 1 is an explanatory diagram showing the configuration of a wafer inspection system according to the first embodiment of the present invention. FIG. 2 illustrates an example of a TEG layout diagram used in the inspection method according to the first embodiment.

Explanation of symbols

10 Wafer Inspection System 12 Probe Card 14 Stage 16 Probe 22 Drive Unit 24 Control Unit W Wafer

Claims (8)

In an inspection method in which electrical measurement is performed on a plurality of measurement objects at different voltages,
Performing electrical measurement of the first measurement object with the first voltage;
Performing electrical measurement of a second measurement object different from the first measurement object with a second voltage lower than the first voltage,
An inspection method, wherein an electrical measurement of the second measurement object is performed immediately before the electrical measurement of the first measurement object.   The inspection method according to claim 1, wherein the second measurement object is a resistance element.   The inspection method according to claim 1, wherein the first measurement object is at least one of a transistor and a capacitor.   4. The inspection method according to claim 1, wherein the first measurement object and the second measurement object constitute a TEG (Test Element Group) that is measured simultaneously. 5. of A probe card having a probe needle to contact a semiconductor element formed on the wafer;
A stage on which the wafer can be moved;
A control unit for controlling the behavior of the stage,
The control unit performs an electrical measurement of the first measurement object on the wafer with a first voltage; it differs from the first measurement object with a second voltage lower than the first voltage. An electrical measurement of a second measurement object on the wafer is performed; and control is performed to perform an electrical measurement of the second measurement object immediately before the electrical measurement of the first measurement object. system.   The inspection system according to claim 5, wherein the second measurement object is a resistance element.   The inspection system according to claim 5 or 6, wherein the first measurement object is at least one of a transistor and a capacitor.   8. The inspection system according to claim 5, wherein the first measurement object and the second measurement object constitute a TEG (Test Element Group) that is measured simultaneously. 9.

Images